Along with what Laurie said, it is very important to know the age of your chameleon and also the size of the terrarium. Most exo-terras are way to small.
As far as the substrate heater, i would not use it. Also, if you have substrate, take it out as this could cause many problems to your cham. Its abreeding ground for bacteria and also the chameleon can ingest it and cause impaction.